ABSTRACT - PROJECT III HLA-G is a nonclassical HLA gene that is expressed primarily in fetal tissues at the maternal-fetal interface, where it plays a significant role in the establishment of implantation. Although the exons of this gene have few polymorphisms, the 5'-upstream region, containing all of the known regulatory elements, is extraordinarily polymorphic. Recently, we reported associations between variants in this gene and miscarriage, and suggested that variation in expression levels of HLA-G mRNA and protein influences pregnancy success. In this application, we propose to directly study the relationship between HLA-G polymorphisms, mRNA expression level, and adverse pregnancy outcomes associated with shallow placental invasion (preeclampsia, preterm labor, and preterm delivery). In Aim 1, we will compare by quantitative SNaPshot differences in mRNA levels in primary cytotrophoblast cells from placentas that are heterozygote for different HLA-G polymorphisms. In Aim 2, we will measure the relative abundance of the differentially spliced transcripts (called G1, G2, G3, G4, G5, and G6) by real time RT-PCR in primary cytotrophoblast cells from placentas with different HLA-G genotypes. In Aim 3, we will assess the effects of polymorphisms on risk for preeclampsia, preterm labor, and preterm delivery in African American and Caucasian patients who deliver at the Chicago Lying-in Hospital and their neonates. Further, we will examine the relationship between HLAG polymorphisms and preterm labor/delivery with and without maternal and fetal infection in these patients. Identifying genetic variants in the HLA-G gene that are associated with adverse pregnancy outcome would implicate this gene and aberrations in its expression in the pathophysiology of the most common disorders in pregnancy. This study has the potential to identify unsuspected mechanisms that influence pregnancy success and may suggest novel therapeutic strategies for women with these disorders.